Re: [PATCH v4 04/12] pktcdvd: Switch to bio_kmalloc()
From: Boaz Harrosh
Date: Wed Jul 25 2012 - 07:30:24 EST
On 07/24/2012 11:11 PM, Kent Overstreet wrote:
> This is prep work for killing bi_destructor - previously, pktcdvd had
> its own pkt_bio_alloc which was basically duplication bio_kmalloc(),
> necessitating its own bi_destructor implementation.
>
> Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx>
> ---
> drivers/block/pktcdvd.c | 115 ++++++++++++++++-------------------------------
> 1 files changed, 39 insertions(+), 76 deletions(-)
>
> diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
> index ba66e44..6fe693a 100644
> --- a/drivers/block/pktcdvd.c
> +++ b/drivers/block/pktcdvd.c
> @@ -522,36 +522,38 @@ static void pkt_bio_finished(struct pktcdvd_device *pd)
> }
> }
>
> -static void pkt_bio_destructor(struct bio *bio)
> +static void pkt_end_io_read(struct bio *bio, int err)
> {
> - kfree(bio->bi_io_vec);
> - kfree(bio);
> -}
Again here, you decided to move the pkt_end_io_read && pkt_end_io_packet_write
functions from below, to above here. Which makes it impossible to find
any bugs by just reviewing the patch.
So I have not reviewed it.
I know that you wanted so you can reference them at pkt_alloc_packet_data.
I'd use a forward reference, in this case. And a move in a next patch. But
this is just me. Perhaps the owner of this code can review it?
Cheers
Boaz
> + struct packet_data *pkt = bio->bi_private;
> + struct pktcdvd_device *pd = pkt->pd;
> + BUG_ON(!pd);
>
> -static struct bio *pkt_bio_alloc(int nr_iovecs)
> -{
> - struct bio_vec *bvl = NULL;
> - struct bio *bio;
> + VPRINTK("pkt_end_io_read: bio=%p sec0=%llx sec=%llx err=%d\n", bio,
> + (unsigned long long)pkt->sector, (unsigned long long)bio->bi_sector, err);
>
> - bio = kmalloc(sizeof(struct bio), GFP_KERNEL);
> - if (!bio)
> - goto no_bio;
> - bio_init(bio);
> + if (err)
> + atomic_inc(&pkt->io_errors);
> + if (atomic_dec_and_test(&pkt->io_wait)) {
> + atomic_inc(&pkt->run_sm);
> + wake_up(&pd->wqueue);
> + }
> + pkt_bio_finished(pd);
> +}
>
> - bvl = kcalloc(nr_iovecs, sizeof(struct bio_vec), GFP_KERNEL);
> - if (!bvl)
> - goto no_bvl;
> +static void pkt_end_io_packet_write(struct bio *bio, int err)
> +{
> + struct packet_data *pkt = bio->bi_private;
> + struct pktcdvd_device *pd = pkt->pd;
> + BUG_ON(!pd);
>
> - bio->bi_max_vecs = nr_iovecs;
> - bio->bi_io_vec = bvl;
> - bio->bi_destructor = pkt_bio_destructor;
> + VPRINTK("pkt_end_io_packet_write: id=%d, err=%d\n", pkt->id, err);
>
> - return bio;
> + pd->stats.pkt_ended++;
>
> - no_bvl:
> - kfree(bio);
> - no_bio:
> - return NULL;
> + pkt_bio_finished(pd);
> + atomic_dec(&pkt->io_wait);
> + atomic_inc(&pkt->run_sm);
> + wake_up(&pd->wqueue);
> }
>
> /*
> @@ -567,10 +569,13 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
> goto no_pkt;
>
> pkt->frames = frames;
> - pkt->w_bio = pkt_bio_alloc(frames);
> + pkt->w_bio = bio_kmalloc(GFP_KERNEL, frames);
> if (!pkt->w_bio)
> goto no_bio;
>
> + pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
> + pkt->w_bio->bi_private = pkt;
> +
> for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
> pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
> if (!pkt->pages[i])
> @@ -581,9 +586,12 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
> bio_list_init(&pkt->orig_bios);
>
> for (i = 0; i < frames; i++) {
> - struct bio *bio = pkt_bio_alloc(1);
> + struct bio *bio = bio_kmalloc(GFP_KERNEL, 1);
> if (!bio)
> goto no_rd_bio;
> +
> + bio->bi_end_io = pkt_end_io_read;
> + bio->bi_private = pkt;
> pkt->r_bios[i] = bio;
> }
>
> @@ -1036,40 +1044,6 @@ static void pkt_make_local_copy(struct packet_data *pkt, struct bio_vec *bvec)
> }
> }
>
> -static void pkt_end_io_read(struct bio *bio, int err)
> -{
> - struct packet_data *pkt = bio->bi_private;
> - struct pktcdvd_device *pd = pkt->pd;
> - BUG_ON(!pd);
> -
> - VPRINTK("pkt_end_io_read: bio=%p sec0=%llx sec=%llx err=%d\n", bio,
> - (unsigned long long)pkt->sector, (unsigned long long)bio->bi_sector, err);
> -
> - if (err)
> - atomic_inc(&pkt->io_errors);
> - if (atomic_dec_and_test(&pkt->io_wait)) {
> - atomic_inc(&pkt->run_sm);
> - wake_up(&pd->wqueue);
> - }
> - pkt_bio_finished(pd);
> -}
> -
> -static void pkt_end_io_packet_write(struct bio *bio, int err)
> -{
> - struct packet_data *pkt = bio->bi_private;
> - struct pktcdvd_device *pd = pkt->pd;
> - BUG_ON(!pd);
> -
> - VPRINTK("pkt_end_io_packet_write: id=%d, err=%d\n", pkt->id, err);
> -
> - pd->stats.pkt_ended++;
> -
> - pkt_bio_finished(pd);
> - atomic_dec(&pkt->io_wait);
> - atomic_inc(&pkt->run_sm);
> - wake_up(&pd->wqueue);
> -}
> -
> /*
> * Schedule reads for the holes in a packet
> */
> @@ -1111,21 +1085,15 @@ static void pkt_gather_data(struct pktcdvd_device *pd, struct packet_data *pkt)
> * Schedule reads for missing parts of the packet.
> */
> for (f = 0; f < pkt->frames; f++) {
> - struct bio_vec *vec;
> -
> int p, offset;
> +
> if (written[f])
> continue;
> +
> bio = pkt->r_bios[f];
> - vec = bio->bi_io_vec;
> - bio_init(bio);
> - bio->bi_max_vecs = 1;
> - bio->bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
> - bio->bi_bdev = pd->bdev;
> - bio->bi_end_io = pkt_end_io_read;
> - bio->bi_private = pkt;
> - bio->bi_io_vec = vec;
> - bio->bi_destructor = pkt_bio_destructor;
> + bio_reset(bio);
> + bio->bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
> + bio->bi_bdev = pd->bdev;
>
> p = (f * CD_FRAMESIZE) / PAGE_SIZE;
> offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
> @@ -1418,14 +1386,9 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
> }
>
> /* Start the write request */
> - bio_init(pkt->w_bio);
> - pkt->w_bio->bi_max_vecs = PACKET_MAX_SIZE;
> + bio_reset(pkt->w_bio);
> pkt->w_bio->bi_sector = pkt->sector;
> pkt->w_bio->bi_bdev = pd->bdev;
> - pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
> - pkt->w_bio->bi_private = pkt;
> - pkt->w_bio->bi_io_vec = bvec;
> - pkt->w_bio->bi_destructor = pkt_bio_destructor;
> for (f = 0; f < pkt->frames; f++)
> if (!bio_add_page(pkt->w_bio, bvec[f].bv_page, CD_FRAMESIZE, bvec[f].bv_offset))
> BUG();
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